Poj Solution 2039

http://poj.org/problem?id=2039

import java.util.*;   
  
public class Main {   
  
    public static void main(String[] args) {   
        Scanner cin = new Scanner(System.in);   
           
        int num = 0;   
        String str;   
        char[][] array;   
        while(true)   
        {   
            num = Integer.valueOf(cin.nextLine()).intValue();   
            if(num == 0)   
                break;   
            else  
            {   
                str = cin.nextLine();   
                array = convert(str, num);   
                System.out.println(getRawStr(array));   
            }   
        }   
    }   
       
    private static char[][] convert(String str, int col)   
    {          
        int toRight = 1;   
           
        int row = 0;   
        if(str.length()%col == 0)   
            row = str.length()/col;   
        else  
            row = str.length()/col + 1;   
           
        char[][] array = new char[col][row];   
           
        int index = 0;   
        for(int i = 0; i < row; i++)   
        {   
            if(toRight % 2 == 1)   
                for(int j = 0; j < col; j++)   
                    array[j][i] = str.charAt(index++);   
            else  
                for(int j = col-1; j >= 0; j--)   
                    array[j][i] = str.charAt(index++);   
               
            toRight++;   
        }   
           
        return array;   
    }   
       
    private static String getRawStr(char[][] array)   
    {   
        StringBuffer sb = new StringBuffer();   
        for(int i = 0; i < array.length; i++)   
            for(int j = 0; j < array[0].length; j++)   
                sb.append(array[i][j]);   
        return sb.toString();   
    }   
}